Restless Eternity
by lovestorywithatwist
Summary: Major Crossfic: Harry Potter/Supernatural/Sherlock - Told from the eyes of the demon. Sherlock, John, and the two Winchesters know something is odd with one of the Gryffindor students, but their own human stupidity gets in the way of them figuring it out. It doesn't help that said student is also in a relationship with the dark Slytherin boy, Jim Moriarty. M/M, One-shot


_**Disclaimer – I don't own any of the characters, nor do I profit from this writing. It's purely for my own and other's enjoyment.**_

**Author's Note: **I literally made this from one of those 'click-and-drag-to-see-what-your-life-is' posts on tumblr. The incredibly dark theme sparked a story, and I really couldn't resist writing it.

* * *

_Death loves final embrace _  
_Your cool tenderness _  
_Memories keep love alive _  
_Memories will never die_

_ - 213, Slayer_

* * *

A particularly loud 'bang' roused me from my sleep.

"Ow! Fuck, Sherlock, watch where you're going, we're going to wake up this half of the castle!"

"It's your own clumsiness, John. I didn't touch you. That was a chair."

"Oh. Right. Sorry. We should still _shut up_."

I groaned quietly, throwing one arm over my eyes. Surely they weren't running off _again_? This was the fifth time this week alone, and those were only the times I'd woken up. I knew exactly what they would be doing, too, and also that their efforts were fruitless; a damn waste of perfectly fine sleeping time for us both. Not that I was about to tell them that. No, in the long run it was better they kept waking me up halfway through the night.

Though, if this continued much longer, I might just go off my rocker and strangle them both.

I shuffled around uselessly in the dark Gryffindor sleeping quarters, unable to find a sufficient sleeping position. I was currently sharing a room with John Watson. He was a short guy, with cropped sandy blonde hair and an open face. He had a firm build, though, and packed a punch from what I'd seen during the Quidditch matches. For some reason, he was also always running around after Sherlock Holmes.

Sherlock Holmes… Well, I guess I could see the appeal. I ran after my own madman after all. But Sherlock was insufferable, never giving – how anyone stood him for over a minute I would never understand. Personally, I found myself desperately searching for a way to leave any room he was in. I think maybe it was the disgust I always saw in his eyes whenever he glanced at me. He had picked right through my barriers, and then found something disturbing underneath that he couldn't explain – hence the late night trips to the library at two o'clock in the morning.

I rolled over in my bed, groping for the extra pillow almost falling off the edge of the bed and hugging it close to my face. Maybe I couldn't stand Sherlock Holmes, but his brother was a fairly different matter. Aggravating, perhaps, but we had come to an easy truce long ago – and now he was possibly the closest thing I could have to a friend.

Friends. I snorted out loud, smirking into the darkness. I certainly didn't need friends. By all means I shouldn't even be here, in the snuggly, warm, Gryffindor common room (or even the castle, really). I had tricked the hat into placing me in Gryffindor and gained quick access into the good books of many of the teachers and students alike.

It was mostly a ruse, and few people talked to me beyond idle conversation, but it was enough to keep me coming back to the school. None of them were intelligent enough to understand. Not even dear little Sherlock and his pet, John, could figure out what I was.

The only person in the whole castle who knew was someone incredibly close to me, in more ways than one. His wide grin flashed before my eyes now, sending a possessive tug at my stomach. _My human_. My delicious, evil little human, always so eager to please (yet somehow never submissive). He was my only equal in anything, and completely mine for the taking.

I felt a warmth pool in my chest, and closed my eyes again, thinking mostly of him. He would help keep Holmes and his pesky, obedient puppy away from us.

With thoughts of my dearest Jim Moriarty, I drifted back into dreams of shadows.

* * *

Mornings were dull. I got ready with the flick of my wand – my magic was far advanced beyond Hogwarts standards, though I did a good job at hiding it – and headed straight for the great hall. It was already completely crowded by members of all houses gathering for breakfast. A quick scan of the Slytherin table told me that, unfortunately, Moriarty had not woken yet, and I'd have to deal with the stares of the Gryffindors for the time being.

Generally I didn't enjoy being around my house. None of them seemed to understand why I was sorted there, and I suppose I couldn't blame them. I stuck out like a sore… thumb, did humans say? (They were so odd. I could think of several better anatomies: an angel with black feathers, a dragon with no scales, a dementor with no robe – I could go on.)

Either way, I ended up at the end of the table, sitting next to the two other largest pains in my ass – the Winchester brothers. Dean was a total dick, but I had a slight fondness for his little brother, Sam. They were only a year apart, and closer than most siblings I'd heard of. I certainly knew none of my brothers or sisters. But then again, I had approximately eight thousand more than them.

I shot a smirk at Sam as I sat down, feeling satisfaction when his eyes widened and flicked quickly down to his food. Dean noticed, of course, and shot me one of those killer glares that I might have found sexy if he wasn't such an imbecile.

I grabbed a piece of bacon and chewed on it thoughtfully, quickly blocking the brothers from my mind. I had bigger matters to deal with, of course, and a plan of action that had to be put into practice as soon as I could. Tonight, I reminded myself, would be the most exciting night since I'd been back on Earth.

Twenty minutes of blessed silence later, a loud clattering alerted me to the arrival of my beloved. Jim was wearing one of his westwood vests underneath an open black robe, and had pinstriped trousers on beneath that. The flashy emerald green stripes of his tie were the only splotches of colour against his otherwise neutral suit.

I leaned into his shoulder almost immediately, suppressing the content growl that rolled up my throat.

"Sleep well, my dear?" he asked, offering me one of those knowing, fake smiles that hinted towards the deeper meaning of,_ "Did those pesky bastards wake you up again?"_

I nuzzled my head into the crook between his shoulder and neck, inhaling the scent rolling off him in waves. Some humans, I had found quite quickly, carried absolutely amazing scents. Others smelled positively putrid. My Moriarty, however, was the most succulent of all the people I'd come close enough to smell. Almost good enough to eat – but I was far too fond of him for that.

"I had a perfectly wonderful sleep," I replied quietly, close enough to his ear that my voice required less power to reach him.

Jim's hand found my knee under the table and squeezed once, showing he understood my own double meaning:_ "Yes those insolent assholes woke me up again. I'm going to kill them if they don't piss off soon."_

We were both quiet for a minute, simply resting against each other, before Jim positively sniggered, turning his face closer to mine so our eyes would meet.

Jim had dark eyes – deep brown in colour, and murky around the edges, as if slate had hardened over his irises. They were nearly as dark as my true eyes. It had been one of the first characteristics I had been attracted to with him. Now they held a playful light, one that no-one else would understand the meaning of, but I had gotten quite good at deciphering.

"Your house looks disgusted. You'd think they'd never seen a gay couple before. Though, having a perfectly adept mind, I know that isn't why they're disgusted."

I grinned back, sparing a glance at the others around the table. Jim was right - at least seven people glanced periodically over at the pair of us, then back again, frowning down at their food. Generally we sat at the Slytherin table, saving them from this sort of awkward moment, but I did enjoy shoving it in their faces. Stupid humans. Though, I suppose their instincts were up to par. They _should_ be nervous around Jim and I.

"Won't have to worry about that much longer, will we?" I whispered back, bringing my lips close to Jim's ear, and gently tugging at the lobe. I could hear a shallow breath whisk out his teeth and I knew he was grinning again. God, I loved that mad smile he got whenever I portrayed affection in public – probably the reason I did it so much.

"I am incredibly excited for those moments," Jim replied just as quietly, turning his face so our noses grazed. Then he pulled back, deftly going to eat more of his breakfast.

That was another thing I loved about Jim. He was unpredictable, and never scared of how I would react. He simply didn't care whether teasing would make something like me angry. And, it most certainly was teasing, because I had to force down the heat in my chest whenever he pulled away like that.

It was a completely addictive high, and Jim knew _exactly _how it made me feel.

"I bloody love you," I bit out, grinning as I got to my own breakfast. Jim simply shot me an innocent look – pointless, as nothing he did could look innocent to me – and continued picking at his eggs.

I suppose our relationship is an odd one on all fronts. 'Love' should not be a product of two dark things in the world. I don't kid myself about being labelled _evil_, as I suppose that is what the _good_ people would refer to me as, though really I am only ambitious and tired of human trivialities. I don't particularly believe in evil, only opposing sides and ploys for power. It is all a game to me. And Jim feels exactly the same.

We are so in sync that sometimes I believe I am an old reincarnation of his soul that got sent straight to hell. If we weren't also opposite in some ways, perhaps I would ask Satan myself. It was those differences that kept us sane, however, while we still managed to blend so perfectly.

Jim was the marrow of my soul – the insides of my structures, supporting and sweetening my existence. I believed I was the same for him. He'd voiced as much, once, slightly unsure whether I would reciprocate or appreciate such a statement, then quite pleased once I did.

It was an odd relationship, but it worked.

The gong of the clock signaled the end of lunch and acted as a signal to get a move on to class. I stretched slowly, feeling the vertebrae in my back crack as I stood. Jim followed suit, drowning the last bit of cranberry juice from his cup as he straightened.

"I will see you after class," he murmured, ducking slightly to pull me into a brisk embrace (in which he playfully squeezed my ass, and I deftly ignored, except for an escaped chuckle) before placing a careful kiss to my temple and withdrawing from the hall, not glancing back.

I followed at a slower pace, ducking out into a small corridor quickly after exiting the great hall and summoning the necessary books for my potions class. The day always started with a bang.

* * *

Ages later, after sitting patiently through all my classes, and managing not to snap at anyone even once – a true miracle on my part, because the tension in the back of my neck had caused painful lacerations to travel down my back all day – it was finally time for the moment I had waited this whole god-awful year in the wizarding school for.

For now I was tucked into one of the big armchairs near the Gryffindor common room's fire. Few students were still awake as the twelfth hour approached. In fact, the only remaining members were none other than my four favorite annoyances: Holmes, Watson, and the Winchesters.

All had put on a good farce of completing homework, but I was aware of their stares. They were determined to sit me out, wait for me to go to bed before they did. They didn't even notice each other doing the exact same thing – not even Sherlock, who's attention was fully trained on me – and so looked even more suspicious in their careful observations than they normally would.

Humans should really stop trying. It was pathetic.

With one swift movement I got to my feet and started to my room. None of the others got up right away, but I knew John would appear in a minute, so I had to move quickly.

With one flick of my wand (I loved those useful little magic sticks; even if I didn't need them to focus my magic, they helped quite a bit) the curtains around my bed had been drawn, and the subtle shuffle of bedsheets sounded close to breathing. I rummaged through my trunk, throwing clothes about as if I had gotten changed, and then headed to the tower's window. It opened with an easy click and within minutes, with the help of a certain pair of leathery, demonic perks, I had reached the edge of the forbidden forest.

Jim was already there, leaning casually against a tree. If my sudden appearance startled him, he certainly didn't show it. I landed gracefully, taking three large strides to reach him, roughly tug him against my chest, and crush his lips to mine. He responded immediately, fingers snatching at my hair to tug harshly at the roots as our mouths slid frantically together. If humans had gotten one thing in the world right, it was kissing.

I grabbed his hips, nails digging into the fabric of the suit he'd been wearing earlier, and no doubt leaving bruises on the delicate skin covering his bones. I knew he loved seeing the dark purple and black marks left by my fingers. As if alerted to my thoughts, Jim moaned against my mouth, sending a flare of desire through my abdomen.

It was with great regret that I finally pulled away, gasping for breath and smirking.

"Later," I promised, gently resting my forehead against his, "Once everything is done. We'll celebrate all night."

Jim let out a frustrated groan, but his own smile was spreading across his lips (which were also bruised, much to my pleasure).

"You're such a tease," he whispered, staring into my eyes intensely in a way only I could understand. We shared stronger feelings than love could ever hope to match: devotion, reverence, and a weakness for the other, bordering on obsession or addiction.

"And yet, you're still here," I whispered back, bending down to brush my lips against his once more before drawing away and immediately getting to work. The sooner this was over, the sooner I would have Jim back in my arms, or preferably in my bed. And, of course, manage to summon my Lord back to Earth. Couldn't forget that part.

I used barely a flicker of magic to sear a mark in the ground, similar to a devils trap, but with different symbols lining the outside. Roughly translated from an old language, it read, _'Gateway of his Lord, who rises from perdition to service us'_.

Jim snatched up a bag from the base of the tree he'd been leaning on, producing ten black candles to sit at each point of the star and each indent. As he lit an incense stick – not necessary, perhaps, but I knew I always loved the smell when I was summoned – I sat at the southern point of the star and closed my eyes.

It would be a long chant, I knew, and one that I would have to improvise pieces for. As phrases poured from my mouth, I couldn't help remembering just how exhausting this whole experience had been. Worth every second of it, of course, but I had come a long way. Centuries of planning had gone into this one night. I'd broken all the necessary seals, performed all the necessary celebrations, and searched the whole damned Earth for the one place the ritual could be performed to its full capacity – in the middle of wizarding school grounds, no less. It was about time I finally raised my Lord from hell.

Everything was quiet until I had made it three fourths through my chanting. I only had five minutes left of praying when I heard the tell tale sound of running, and knew exactly who it was, because _they just had to show up_-

"Jesus Christ, what the hell are you two doing?" I didn't open my eyes or pause in my mantra to spare a glance at the familiar voice of John Watson.

"John, get back, _he's not_-"

A loud bang rung out, and I knew Jim hadn't paused to gloat or explain, but simply begun the duel. He knew tonight was not one we could afford to mess up. I kept my ears open, though, worried he would be overwhelmed by the two Gryffindors.

He seemed to be holding his ground though, I thought proudly, as the sounds of fighting continued. I was nearly done, rounding on the last few phrases, formulating my own twist to the end of the chant, when more voices joined the fray. My breath nearly hitched in fury, and I managed to spit out the last of the chant before whirling away for a moment to stare at the scene in front of me.

Jim, my beautiful human, was calmly deflecting spells from both Watson and Holmes, and sending them back with as much ease. The crook of his mouth, however, was a red light telling me that that he was having troubles keeping up. Yet, so far he had managed to, and that made a fierce feeling of pride rise up further to snarl happily in my chest.

Also running towards the fray were, of course, the Winchester brothers, with Dean in the lead. I saw a glint of metal in his hand, just a flash of silver as he raised his arm, and had a second to consider what he was about to do. _Bastard._

"_Nullus hominum tetigerit meum!_" the words were guttural roar as I moved, faster than the Winchesters had expected, to block Jim from the assault. Dean's finger pulled the trigger of the gun, but I easily deflected the bullet in addition to the spells Watson and Holmes were still shooting.

I surprised everyone into a sudden halt, and we stood there for a long time, examining each other.

"What sort of ritual are you doing? Are trying to raise a fucking demon or something?" Dean was the first to speak, obviously disgusted in me. I let out a cold, icy laugh, closer to a shriek than a sound of amusement.

"Isn't it obvious yet?" I hissed out, stepping forwards._ How were they so blind?_ They could not see them, but the great leathery wings at my back had extended to their full span, protecting Jim behind me. My dearest hadn't said a word, though I could feel his calm emotions behind me, settling my unbent rage enough to remember the real reason we were here.

"Why don't you step away from there and we'll just forget this ever happened-," Sam started to suggest, but stopped in a horrified silence once I cut him off with a real growl. It reverberated off the trees around me, sending the waves back to vibrate up my spine.

"My real name is Sitri. I am a prince of demons," I nearly purred, reveling in the looks of surprise and terror by all four humans. Stupid, insolent beings. They had no respect for power or proper religion. I began to hope they would stick around just so I could gut them.

"Stop these tricks, they're pathetic," Sherlock's lazy drawl suddenly became disgustingly, completely unbearable that very moment, and I decided he would be the first to die. I wanted him to feel it, too, every second of my claws tearing through his frail body.

I advanced on him, snorting derisively when John flung himself in front of his friend, fear spread across his features so clearly I could taste the horror on him.

"John," Sherlock muttered in surprise from behind him, and I resisted the urge to roll my eyes.

"He's doted on you, Sherlock, and now you're both going to die. Shame it's too late to claim your undying love," I said softly, feeling the power rise up inside me. My hands began to change, flickering slowly into my true form as curled, thick claws. I pulled my wings through as well, arching them high above everyone.

"I'm going to enjoy making this painful. You two idiots woke me up nearly every night for a month, and I enjoy my sleep," my voice trailed off into my cold, true voice, the one that rang with power and chaos. I could feel my aura reaching towards John and Sherlock, taste their desperation and confusion, along with the tiny flickers of hope that they would live. It would have been laughable if it wasn't so pathetic.

I was nearly at John when the two humans glanced at the Winchesters in expectation, and then I knew I had gotten too far from my dearest. Sure enough, while Jim had turned his attention to me, following my steps with awe – I was flattered, because he so loved my true form, and worshiped every part of me, but now really was a horrible time – Dean had loaded the gun and trained it at my lover's back.

I should have known there was something wrong, but I didn't care - _Nullus hominum tetigerit meum_, I thought again, possessively, and flew across the space between us to get in the way of the bullet. If Jim had been on an angle that I could have used my magic without hurting him, maybe everything would have turned out differently, but they did not. It hit me right over my heart, with a jarring impact that left me breathless.

There was a sudden, fierce pain in my chest, unbearable burning, and then a screech that I didn't understand was mine until I had finished. The bullet was iron, blessed with holy water, and had a sigil drawn on it. I fell, slowly, eyes flicking up to meet those of Dean Winchester. I should have known he would be the one to do it.

Thinking back, I wouldn't have done anything differently. Jim cradled my head, eyes wide in shock and grief, and he mumbled that it wasn't fair to leave him now. I blinked back slowly, finding it hard to form words.

"No, no, don't you dare leave me, not after everything I've done for you," he whispered in my ear, pressing his hands along my chest and then cupping my face, as if unsure where to keep them. "Fix yourself," he demanded, slightly louder. I let out a soft sigh, feeling the life oozing from my borrowed form. I wouldn't last long now.

"Damnit, _fix yourself_!" Jim roared, eyes blurring with angry tears. With effort, I lifted one hand to gently press his head down until his lips ghosted just over mine.

"I can't," I mumbled against him. "I will be sent back to hell."

"I'm going to kill him for this," Jim hissed back, somehow still softly. "I won't rest until he's been destroyed."

"My human," I growled fondly, tugging his head further down to share one last, short, fevered kiss. I could feel the smoke rising from my chest as my body began to disintegrate.

"I will wait for you, my beautiful, dark soul," I vowed breathily, and then awareness slipped from my mind as I whisped upwards into the air as smoke. For a second I wrapped around Jim, capable only of feeling a deep devastation at being pulled away from him, before the Earth claimed me and sent me back to where I belonged.

I would wait.


End file.
